A Direct Electrode-Driven Immobilized Catalase for Biocatalysis of Peroxides

摘要

The direct electrochemistry of catalase (Cat) immobilized in agarose hydrogelnfilm on glassy carbon (GC) electrode was investigated. A pair of well-definednand quasi-reversible redox peaks both in aqueous buffer and ethanol-aqueous mixturenwas obtained. The formal potential (Eu000e’) indicates the reactions origin fromnthe direct electron transfer between the CatFe(III)/(II) couple and the electrodensurface. The Eu000e’ is linearly dependent on solution pH (redox Bohr effect), indicatingnthe electron transfer of the CatFe(III)/(II) redox couple accompanied withnthe transfer of a proton. The electron transfer can be facilitated in ethanol-aqueousnmixture for the reason of partial dehydration of the distal heme pocket. The waternpools in agarose hydrogel play an important role in preventing either the changenof conformation or the inactivity of Cat from polar organic solvent. Cat retains itsnoriginal conformation in the agarose film that was confirmed by UV-Vis spectranand electrochemical behaviors in comparison to the controlled experiments usingnfree hemin. The catalytic reactions to peroxides (hydrogen peroxide, cumenenhydroperoxide, t-butyl hydroperoxide, 2-butanone peroxide) using Cat-agarosenmodified electrode were also explored both in aqueous buffer and ethanol-aqueousnmixture. The method could be application to the preparation of the hydrogel basednthird generation biosensors or bioreactors in organic media.